cc: Make OutputSurface::SwapBuffers pure virtual

cc/test/test_context_support.cc

Index: cc/test/test_context_support.cc
diff --git a/cc/test/test_context_support.cc b/cc/test/test_context_support.cc
index 88127d582d49fe3e6bc9343a7cee8ce6db9dfd62..f74f69253f2311c5f00bfd29b9a0dd8b876209aa 100644
--- a/cc/test/test_context_support.cc
+++ b/cc/test/test_context_support.cc
@@ -10,8 +10,7 @@
 namespace cc {
 
 TestContextSupport::TestContextSupport()
-    : last_swap_type_(NO_SWAP),
-      weak_ptr_factory_(this) {
+    : weak_ptr_factory_(this) {
 }
 
 TestContextSupport::~TestContextSupport() {}
@@ -59,7 +58,6 @@ void TestContextSupport::SetScheduleOverlayPlaneCallback(
 }
 
 void TestContextSupport::Swap() {
-  last_swap_type_ = SWAP;
 }
 
 uint32 TestContextSupport::InsertFutureSyncPointCHROMIUM() {
@@ -72,8 +70,6 @@ void TestContextSupport::RetireSyncPointCHROMIUM(uint32 sync_point) {
 }
 
 void TestContextSupport::PartialSwapBuffers(const gfx::Rect& sub_buffer) {
-  last_swap_type_ = PARTIAL_SWAP;
-  last_partial_swap_rect_ = sub_buffer;
 }
 
 void TestContextSupport::ScheduleOverlayPlane(